In the liquid crystal panel industry, the bottom gate structure is usually adapted in the current array substrate, and the on-state current of the bottom gate structure is heavily depend on the width to length ratio of the channel. Due to the limited of the manufacturing conditions of the current array substrate, a length of the channel to reach within the level of 5 micrometer, it has been very difficult to narrow, and some of the aperture ratio would sacrifice by increasing the width of the channel. Thus, the width to length ratio of the channel in the conventional technology cannot be increased; thereby the on-state current of the bottom gate structure cannot be increased.